Are const_iterators faster?

Question

Our coding guidelines prefer const_iterator, because they are a little faster compared to a normal iterator. It seems like the compiler optimizes t

Answer 1

I can't see why they would be - constness is a compile time check. But the obvious answer is to write a test.

Edit: Here is my test - it gives identical timings on my machine:

#include 
#include 
#include 
using namespace std;;


int main() {
    vector  v;
    const int BIG = 10000000;
    for ( int i = 0; i < BIG; i++ ) {
        v.push_back( i );
    }
    cout << "begin\n";
    int n = 0;
    time_t now = time(0);
    for ( int a = 0; a < 10; a++ ) {
        for( vector ::iterator it = v.begin(); it != v.end(); ++it ) {
            n += *it;
        }
    }
    cout << time(0) - now << "\n";
    now = time(0);
    for ( int a = 0; a < 10; a++ ) {
        for( vector ::const_iterator cit = v.begin(); cit != v.end(); ++cit ) {
            n += *cit;
        }
    }
    cout << time(0) - now << "\n";;

    return n != 0;

}